Pipe bending machine



Mar'cl'n l, 1932.- l E, VOLLMERHAUS I 1,847,200

1 -v PIPE BENDING MACHINE Filed sept. A21, 1929 l Inven tot: Ewal. Vollmerh aus.

rafenfedpMar. 1.1932

PAT-ENT oFFlcE PIPE BENDING ramo-Hirn?.` I

Appiication ined' sept-emherl 21, 192s, seria1 No. 394,225', and 1n Germany July 25, 1929.

My present invention` has foi' its objectl to provide a bending machine for bending seamless boiler tubes, welded steam and gas pipes and other similar metal tubes or pipes bend them in a cold state in the known bendingmachines and devices. f The minimum oradius which it was possible to bendin a cold,

state was about 4 to 5 times the diameter of .the tube 'However it is also desired to have bends with a .radius of about 11/2 times the diameter of the tube and for this operation the known bending machines and devicesY were not convenient. Such bending had to be madein a hot state' of the tubes which was expensive in fuel, time, work and other expenses.

The improved bending machine provid` 25.ed by my present invention comprises a chain formed of individualmembers or links,

which will beclosely appliedl against each other at the bending point ofthe tube in thel bending operation, said members or links be-v ing apertured or recessed accordingito the` radius ofthe tube, whereby they are enabledl to embrace the tube on the outer half portion l of the surface to be'bent..y The inner hal portion of the surface of the tube will be embraced ign the well known way by the known bending body,` whereby the tube ywill be completely embraced not only at the bending ypoint inthe bending operation, but also on the complete bent portion or length; Consequently a distortion of the tube in the bending operation will be completely impossible.

In thefaccompanying drawings I have illustra'ted one preferred embodiment of my 45. invention section on line 2 2 of from being moved by the high pressure pro- Fig. 4 is a cross section 011 line 4 4 of Fig. 1. f Fig. 5 is an enlarged horizontal section of the bending members, and y Figs. 6 to 8 show details of the bending 55 chain. n i Referring to the drawings d is the machine .frame and?) is the known bending body rotatably mounted on said frame and adapted to be rotated inithewell-known way by means of gear-wheels c in the bending operation. The bending body b has an extension or arm e recessed according to the radius of the tube to be bent and connected to a clamping device f providedwith a tightening screw g 5 and. a-clampingjaw h recessed according to the radius of the tube. i Upon tightening the screw will be firmly clamped. y

. Arranged on the outer surface of the tube d is a bending chain formed of links z' and side plates lc. The side plates lo are pivotally y, the tube d connected to the links z' as nearV as possible to the sides o f the tube andthe iirst link is arranged on 4the clamping device f. The 7.5

`links i of the chain are recessed according to the radius of the tube d and connected to each other in such. a way that in the bending operation they will be closely applied against each other. at their. inner edges, as best shown in Fig.. 5, whereby the tube d will be completely embraced onl its entire peripheryat the bending point as Well as in the bending operation on the whole length or portion Q bent. Therefore it will not be possible for 8 thetube d to be' distorted at any point and in any direction` Y f Provided at'the bending point is a pressure member m having a bevelled pressure strip n. The pressure memberm is slidably arranged and'adapted to be' pressed against the chain by means of a screw threaded spindle p screwed into a slidevo and acting on :an intermediate pressure bolt g. vThe latter is detachably connected to the pressure member m and threadedspindle p and upon the backward rotation of the latter said pressure bolt g will move the pressure member m backwardly. slideo is prevented screws 1" and moreover by a strip t inserted behind an extension or shoulder s on the mabe drawn forwardly. Thus it Will be seen,

chine frame a or by a threaded spindle (not shown) to be appliedr thereto. f

Arranged, at the end of the bending chain is a link uf. having an outer bevelled face and intended to' bemoved against the pressure strip n at the end of the bending operation, as clearly shown in Fig. 5, whereby the end of the tube d will be prevented from being iattened upon the removal of the well known bending mandrel o. It will fbe obvious that the-'link or memberV u may be omitted.

The bending mandrel o is supprted in a bracket w arranged the nearest possible to the ybending point, in order to prevent said mandrel from being bent, which would occur owing to the excessive stresses produced in the bending operation on a little radius without said bracket w, omitted in known bending machines -Referringl to Fig. 4 'the bracket fw has jaws adj ustable by means of screws, whereby the bending mandrel may be adjusted eXactly. The bending mandrel o may be moved and `locked in position by means of the well known slidable bracket y.

Attached to the bendingvchain is.\a cord or cable z, provided with' a weight and serving to remove said chain upon the bending of the tube d.

After the tube d has been clamped in the clamping device f, the first link i of the bending chain Willbe vpressed against the tube d by' means of the pressure strip n by the tightening of the threaded spindle p, whereby the tubed will be firmly pressed against the bending body b. Upon the rotationof the bending body b the bending chain will that the tube d will be completely enclosed onits entire periphery from the beginning of the bending and during the wholebending operation, because the bending chain is permanently .under the high pressure; required for bending the tube d. Therefore the tube cannot be distorted and the links c' of the lbending chain will produce al stretching or drawing and smoothing action on the walls ofthe tube, whereby the formation of folds and grooves willbe prevented.

Having now fully described my said `in vention, what I claim and desire to secure by Letters Patent, is:

l. In a pipe bending machine the combination with a suitable frame, a rotatable bending body and a slidable bending mandrel on said frame, of a bending chain having links adapted to embrace the outer surface of the tube or pipe to be bent in cold state and connecting plates pivotally connected to 'said links on pivots tangent to the surfaces of the links that engager the outer portion of the bent pipe. I

sald frame,. of a bending chain having links' adapted to embrace lthe outer half surface of the tube or pipe to be bent in a cold state and connecting plates pivotally connected to said links on pivots tangent to the surfaces of the links that engage the outer portion ofthe bent pipe,a pressure strip or bar having a bevelled working face, 'and means for slidably displacing said bevelled bar towards the links Vof th'e chain wherebythe latter willbe pressed against the tube or pipe to be bent.

3. In a pipe bending machine the combination with a suitable frame, a rotatable bendingibody and a slidable bending mandrel on said frame, of a bending chain having links adapted to embrace the outer half surface of the tube or pipe to be bent in a cold state and connecting plates pivotally connected to said links on pivots tangent to the surfaces of the links that engage the outer portion of the bent pipe, a particular Aend link having a bevelled router face on said bending chain, a pressure strip .or bar having a bevelled working surface, and.means for slidably pressing said bevelled bar against said bevelled end link.

4. In a pipe bending machine the combinaai tion with a suitable frame, a rotatable bending body and a slidable bending mandrel on said frame, of a bending chain having links adapted to embrace the outer half surface of the tube or pipe to be bent in a cold state, and connecting plates pivotally connected to said links on pivots tangent to the surfaces of the links that engage the outer portion of the bent pipe, a bracket supporting the bending mandrel immediately after the end link of the bending chain, and adjustable jaws on said bracket.

5. In a pipe bending machine the combination with a suitable frame,a rotatable bending body and a slidable bending mandrel on said frame, of a bending chain having links adapted to embrace the outer half Asurface of chain.

EW'ALD VOLLMERHAUS.

the tube or pipe to be benj; in a Vcold state 

